2011 Fiscal Year Final Research Report

Study of the interrelationship between Legionella pneumophila and free-living amoeba under the condition of natural water temperature to solving legionaires' disease

Research Project

Project/Area Number	21560573
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Civil and environmental engineering
Research Institution	Toho University
Principal Investigator	OHNO Akira 東邦大学, 医学部, 講師 (40223903)
Project Period (FY)	2009 – 2011
Keywords	土壌 / 水環境
Research Abstract	It was demonstrated that L. pneumophila shifted into a VNC(Viable but not Culturable) mode inside the Acanthamoeba castellanii cells at a temperature of 15 degrees C by the combination of cultural method, real time PCR(RTPCR) and EMA treated real time PCR(EMA RTPCR), and by transmission electron microscope observation. On the other hand, the shift into VNC state was not observed in Acanthamoeba polyphaga and Haltomannella vermiformis. Culturable L. pneumophila cells were not detected in periodic survey of river water at fixed-sampling points targeting two major rivers in the Tokyo area. A few viable Legionella cells were detected by the combination of RTPCR and EMA RTPCR, however the numbers of viable cells were approximately-same without relation to season. The detection of free-living amoeba(FLA) by PCR showed that the genus Haltomanella was predominant in the sampling points and A. castellanii was not detected. The absence of FLA species that the interrelationship with L. pneumophila is affected by water temperature or few chances to encounter host amoeba by flow of the river might be cause of this result.

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